Hangman fracture, also known as traumatic spondylolisthesis of the axis, is a fracture which involves the pars interarticularis of C2 on both sides, and is a result of hyperextension and distraction.
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Epidemiology
These injuries account for 4-7% of all cervical spine fractures and up to 22% of axis fractures 6.
Clinical presentation
Post-traumatic neck pain after a high-velocity hyperextension injury is the most common presentation. Neurological impairment is seen only in 25% of patients.
Pathology
This is known as a 'judicial lesion' as injury results from forces delivered by a noose, which was placed with the knot towards the side of the neck, next to the angle of the mandible/mastoid process. However, it was not seen in many of those who were judicially hanged, with asphyxiation being the usual mode of death. This fracture is virtually never seen in suicidal hanging.
Major trauma in hyperextension, such as a high-speed motor vehicle accident, is, in fact, the most common association – especially in fatal cases.
Classification
Hangman fractures are commonly categorized by the degree of angulation or translation according to the Levine and Edwards classification 8, which is a modification of the original system described by Effendi 7.
C2 fractures can also be classified under the AO Spine classification of upper cervical injuries as bony injury only (type A), tension band/ligamentous injury resulting in angular instability (type B), or translation (type C).
Hangman fractures are described as "typical" if only involving the pars interarticularis and as "atypical" if one or both sides courses through the posterior body of the axis 10. Some subclassifications of atypical hangman fractures have been proposed 11,12.
Radiographic features
Radiography and CT demonstrate the findings:
typical: bilateral C2 pars interarticularis fractures
atypical variant: one or both sides of C2 has a coronal plane (vertically oriented) fracture through the posterior vertebral body instead of the pars interarticularis
possible alignment abnormality: anterolisthesis of C2 on C3 or angulation
Extension of the fracture to the transverse foramina should be sought, raising the possibility of vertebral artery injury.
Treatment and prognosis
Treatment can be a collar, halo, or surgical fixation.
Atypical hangman fractures may have a higher frequency of neurologic compromise than typical hangman fractures 11,12.
History and etymology
The term "hangman fracture" was introduced by Schneider in 1965 5. Strictly speaking, the fracture is misnamed and should more correctly be called "hangee" fracture. As a historical note, there are four methods of judicial hanging, and the process is more complicated than may be evident at first glance.
Practical points
check for an extension to the transverse foramina and, if present, vertebral artery injury should be considered